This causes errors under JRuby 1.7.2 through 1.7.4 (at least), doing `Time.now === ""` triggers a `no implicit conversion from nil to integer`. Arguably this is a JRuby issue as that works fine under MRI, but it makes it impossible to set any time values on JRuby through MM.

Perhaps change this to the check used for Extensions::Date?

`if !value || (value.instance_of?(String) && '' === value)`